Method of making metallic bellows



Feb. 4, 1930. A. o. SCHARER METHOD OF MAKING METALLIC BELLOWS FiledSept. 17. 1925 Air Pump IXVENTOR Arnoki ofichurer Patented Feb. 4, 1930UNITED "STATES PATENT OFFICE ARNOLD O. SCHARER, OF CLEVELAND, OHIO,ASSIGNOR TO THE BISHOP & BABCOCK COMPANY, OF CLEVELAND, OHIO, A.CORPORATION 01 OHIO METEOD OF MAKING METALLIC BELLOWS Application filedSeptember 17, 1925. Serial No. 56,875.

The present invention relates to a method of making metallic bellows,and is more particularly directed to an improved method of convertingangular corrugations previously 5 formed in a thin tubular wall intosubstantially parallel corrugations with a minlmum of effect and timeand in such a way as to produce substantially parallel corrugations andprevent any irregularities or cocking of one or more of thecorrugations, as has been the trouble with methodspreviously used forthis purpose. A further object of the invention is the provision of acombined method for thus converting angular into parallel corrugationsby collapsing of the tube len h while at the same time testing the metal 1c bellows for any minute leaks or openings 1n the tube wall whichmay. have been formed during the previous manufacturing steps. To theaccomplishment of the foregoing and relatedends, said invention, then,consists of the means hereinafter fully described and particularlypointed out in the claims.

The annexed drawing and the following description set forth in detailcertain means and one mode of carrying out the invention, such disclosedmeans and mode illustrating, however, but one of various ways in whlchthe principle of the invention may be used.

In said annexed drawing Fig. 1 is a view more or less diagrammatic incharacter showing one form of apparatus adapted to carry outmy improvedmethod, in which apparatus there is positioned an extended corrugatedtubular wall ready for collapsing; and Fig. 2 is a side elevation of ametallic bellows after this collasping and testing operation.

One method of manufacturing metallic bellows consists in forming broadcorrugations in a cylindrical tube, the corrugations having angularlyrelated sides and being broad relative to the desired breadth ofcorrugation which is finally desired in the bellows, after which thesecorrugations are converted into parallel sided ones by a longitudinalcollapsing operation which slightly increases the outside diameter ofthe corrugation, decresaes the inside diameter and very greatly narrowsthe angular opening in both the outer and inner corrugations by acombined bending and stretching action. This operation may be performedby various methods, one of which is described in a copendmg applicationfiled by William R. Zimmerman, erial No. 60,786, and the method theredescribed is entirely satisfactory, except that it requires a certainamount of time to dispose, collapse, and then remove each of thepartially corrugated bellows from the collapsing apparatus since thebellows must be mounted about an internal die, after which a plungermust be brought down into contact with one end of the bellows to performthis collapsing step. The present method has been found to saveconsiderable time over that in the above-named application, and at thesame time to effect atesting of the bellows which is substantially theequivalent of the service to which the majority of such bellows are put,that is, the testing pressure is substantially as high as the pressuresin use to which the bellows is subjected.

My improved method of collapsing consists, briefly stated, in mounting abellows having one closed end with its open end in position against asuction plate formed in suitable material to give a tight joint at thisend of the bellows, after which suction is applied to the interior ofthe bellows to produce as high a vacuum as possible therein, thusallowing the atmospheric pressure acting upon the closed end of thebellows to collapse the bellows without any other means. It will beapparent that the total pressure acting to collapse the bellows issubstantially the product of the number of square inches in the closedend multiplied by the atmospheric pressure minus the internal pressurestill remaining in the bellows after the air therein has been exhaustedby suction as far as possible. At the same time there is atmospheric airpressure acting against ever portion of the outer surface of the bellowsduring the collapsing operation, and this is precisely the action towhich the bellows is subjected in service, since in service the pressureis acting against the inner or outer walls of the bellows during themovement of the bellows, and not while the bellows is at rest. In manyinstances bellows are subjected to very low pressures, such, forexample, as 1n packless valves, while in steam traps and certain typesof thermostats, air motors and the like, the

pressure exerted is rarely above 20 pounds per square inch, and in manvoases does not exceed 15 pounds per square inch, which is the pressureexerted by the atmosphere during the testing operation described above.In Fig. 1 there is shown a plate 1, to the upper surface of which issecured a suction plate 2, which may be formed of rubber or 1 similarmaterial. Both of the plates 1 and 2 are provided with aligned centralopenings which lead to, and connect with, a conduit 3 extending to asuitable air pump 4, while a vacuum gauge 5 is also connected to theconduit 3 for registering the degree of vacuum which is produced in thebellows. The air pump can be operated continuously while the operatorwill merely position a bellows: 6, having one closed end 7, in invertedposition upon the plate 2, that is, withthe open end of the bellowsagainst the plate. The air will be rapidly exhausted from the bellows,allowing the atmospheric pressure to collapse the bellows quickly anduniformly, and this will occur provided there is no leak in the bellowsat any point. If there is a leak, then of course the bellows will note01 lapse, or will collapse so slowly or incompletely that the operatorcan readily detect the difference and can throw the bellows out. As soonas the bellows is collapsed the valve 8, interposed in the conduit 3,may be closed,

thus interrupting the suction and allowing atmospheric air to flow intothe bellows through a port 9, when the operator can readily remove thebellows from the plate and position the second bellows for collapsing.It has been found in raotice that this method of collapsing be lowsprovides a greater uniformity in the spacing and conformation of thevarious corrugations than is possible with other methods, while theaction is extremely rapid. In addition to these advantages the bellowsis automatically tested during, and by,'the collapsing operation.

Other modes of applying the principle of myinvention may be employedinstead of the one explained, change being made as regards the means andthe steps herein disclosed, proing a high vacuum therein tosimultaneously test and collapse the same longitudinally to bring saidcorrugations into proximity to each other said last step effecting thepermanent modification of the conformation of the several corrugations.I

4. In a method f making'flexible corruated metal walls, the steps whichconsist in orming substantially parallel s aced corrugations in a thinwalled metal tu e, and then subjecting such tube to an evenlydistributed endwise pressure sufliciently severe to permanently changethe contour of said corrugations and collapse the same upon each other,while simultaneously testing the wall of said tube for leaks. Signed byme this 11 day of September,

ARNOLD 0. SCHARER.

vided those stated by any of the following claims or their equivalent beemployed.

I therefore particularly point out and distinctly claim as myinvention 1. In a method of making flexible corrugated metal walls, thesteps which consist in forming substantially parallel spacedcorrugations in a thin-walled metal tube, and then subjecting said tubeto suction to cause longitudinal collapsing of the same and asimultaneous permanent modification of the conformation of the severalcorrugations.

2. In a method of making flexible corru-

